8 ROS2 -Writing a simple publisher and subscriber (Python)

Installing MS Code

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Create a package

Open a terminal and run:

cs

ros2 pkg create --build-type ament_python py_pubsub

cd py_pubsub/py_pubsub/

wget https://raw.githubusercontent.com/ros2/examples/humble/rclpy/topics/minimal_publisher/examples_rclpy_minimal_publisher/publisher_member_function.py

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Explaining the code

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Add dependencies

Open package.xml with your text editor, add these lines:

<exec_depend>rclpy</exec_depend>
<exec_depend>std_msgs</exec_depend>

Open the setup.py file, add these lines.

entry_points={
        'console_scripts': [
                'talker = py_pubsub.publisher_member_function:main',
        ],
},

Write the subscriber node

In the same terminal and run:

cs

cd py_pubsub/py_pubsub/

wget https://raw.githubusercontent.com/ros2/examples/humble/rclpy/topics/minimal_subscriber/examples_rclpy_minimal_subscriber/subscriber_member_function.py

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Explaining the code

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Open the setup.py file, add these lines.

entry_points={
        'console_scripts': [
                'talker = py_pubsub.publisher_member_function:main',
                'listener = py_pubsub.subscriber_member_function:main',
        ],
},

In the same terminal and run:

ros2 run py_pubsub talker

Open another terminal and run:

ros2 run py_pubsub listener

Reference : https://docs.ros.org/en/humble/Installation.html